“Before Midnight” delivers in the difficult ways it absolutely must: It is as good a movie as its predecessors, “Before Sunrise” and “Before Sunset,” which by now have practically achieved classic status.

And it advances the characters, Celine and Jesse, in ways audiences can believe. Yes, these are the same people, but in different lives now, and in their early 40s.

The first two films were courtship dramas and wildly romantic. It might have seemed that all they did was talk, but they were seducing each other, and the question was always whether it would work, whether they would get together.

For “Before Midnight,” the same dramatic strategy was no longer possible. Now the question is whether they will stay together, and this makes for an entirely different movie, not just nonromantic but anti-romantic, a movie that can make an audience sad about what sometimes happens to lovers a few years down the line.

If you're among the people who want to know absolutely nothing about Celine and Jesse's situation going into “Before Midnight,” it's time to check out of this review right now ...

OK, they're gone, let's talk: Nine years have past. Jesse is divorced from his wife and now lives with Celine. The two are, in all ways but legal, as married as people can be. And they have adorable twin girls, who are 8 years old, the product of the union that commenced just minutes after “Before Sunrise” ended.

Jesse (Ethan Hawke) is a successful novelist, with three books under his belt, the first two of which were thinly fictionalized versions of his romance with Celine. And Celine (Julie Delpy) is an environmental activist, who is considering taking a job with the government.

When Jesse says she should take it, she is against it. When he agrees that she shouldn't take it, she is for it. So he backs off and tries to say nothing, and that, in essence, is Jesse's life these days.

Like its predecessors, “Before Midnight” takes place in a beautiful location, on the Peloponnese peninsula in Greece, where Jesse and Celine are coming to the end of a long vacation. Jesse's son from his previous marriage, having spent the summer, has now gone home to Chicago, and Jesse wishes he could see more of him. Celine knows what this means — that Jesse, though he doesn't say it, would like them to move from Paris to the United States. This becomes a source of mutual contention and stress for the rest of the picture.

With other films, you can argue about the characters and be sure you're right, but in “Before Midnight,” the characters are so complex that talking about them is like talking about real people.

In “Before Midnight” Celine has a legitimate fear and a legitimate grievance. She knows that, if Jesse has his way, she might soon be living in the United States, with either no career or at square one.

She can also see that he has developed that distinctly male weapon of blithe reasonableness, designed to win through friendly-seemingly disengagement. Understandably, she wants to shake him up, crack through the facade and get through to him.

But “Before Midnight” gives poor Jesse much to live with. I suppose anyone paying attention to the previous films might have guessed Celine would be difficult for the long haul, but she's that and more. Celine airs their dirty linen in public, mocks him sexually and belittles his talent. She's borderline rude to his fans and denies the foundational mythos of their love, that the two nights depicted in the previous films were fated and magical. Celine's default setting with Jesse is to act like he's an idiot — that his idiocy is so understood as to require no explanation.

If Celine isn't quite more trouble than she's worth, she is inches away. Millimeters. Yet that, in a sense, is part of the film's artistry. The drama depends on the audience's believing in this romance and that it should continue, and yet the movie pushes that faith to the brink, though not beyond it.

Thus, the delightful conversations of the previous movies have given way to arguments. But these arguments, long and convincing, are impressively written, and in their length and depth, unprecedented in American cinema.

Alas, yes, those romantic nights you once wished you were on have turned into the relationship you're so glad you're not in. Nonetheless, “Before Midnight” is fascinating to watch, and so long as Celine and Jesse are communicating, there's still hope.